1. Field of the Invention
The present invention relates to scroll compressors, and more particularly, to a wrap structure of each scroll in the scroll compressor for compressing refrigerant as an orbiting scroll orbits a fixed scroll.
2. Background of the Related Art
In general, the scroll compressors are mostly used in room air conditioners or car air conditioners as the scroll compressors have low noise, and small sized and light weighted, in which one pair of opposite scrolls form a compression chamber, in which the refrigerant is compressed. FIG. 1 illustrates a section of a related art scroll compressor, referring to which the related art scroll compressor will be explained.
Referring to FIG. 1, there is an enclosed shell of a body 1 having an inlet tube 11 and an outlet tube 15 connected thereto for drawing and discharging the refrigerant, respectively. There is a fixed scroll 8 in an upper part of the body 1 having an outlet 12 at a central part 12 thereof and a wrap 8a of an involute curve projected downward from a bottom thereof. Also, there is an orbiting scroll 7 under the fixed scroll 8 orbitably coupled with the fixed scroll 8 in correspondence thereto having a wrap 7a of an involute curve projected upward. Side surfaces of the wraps 8a and 7a on the fixed, and orbiting scrolls 8 and 7 are made to be brought into contact as well as fore ends of the wraps 8a and 7a and scroll dish plates (disks the wraps are formed thereon), to form a compression chamber (a space which encloses refrigerant therein and is involved in gradual reduction for implementing compression).
The orbiting scroll 7 has a crank shaft 6 fixed to a bottom thereof for orbiting the orbiting scroll 7 as the crank shaft 6 transmits a rotating force from a motor part 5, provided in a lower part of the body 1, to the orbiting scroll 7 via an Oldham ring 9 that prevents rotation of the orbiting scroll 7, to reduce a volume of the compression chamber gradually to compress the refrigerant trapped between the two scrolls 7 and 8 and discharge through the outlet tube 15.
FIGS. 2Axcx9c2D illustrate the steps of a process for compressing refrigerant in a related art scroll compressor, referring to which the operation of the related art scroll compressor will be explained in detail.
Upon application of power to the motor part 5, the crank shaft 6 rotates to rotate the orbiting scroll 7 fixed on a top thereof. In this instance, the orbiting scroll 7 is made to orbit spaced from a center of the crank shaft 6 by a preset orbiting radius in a state rotation is prevented by the Oldham ring 9. As shown in FIG. 2B, low temperature and low pressure refrigerant 20 drawn into the body 1 through the inlet tube 11 after being heat exchanged at an evaporator during the foregoing process is the compression chamber through refrigerant inlets 21 and 22 formed by the wraps 8a and 7a on the fixed scroll 8 and the orbiting scroll 7, respectively.
Then, as shown in FIGS. 2C and 2D, as the orbiting scroll 7 keeps to orbit, the refrigerant is involved in gradual decrease of a volume thereof and flows toward a central portion of the compression chamber, i.e., to a location where the outlet 12 of the fixed scroll 8 is formed. It can be known that, as explained, the refrigerant is compressed to high temperature and pressure as the refrigerant is involved in gradual decrease of volume during the refrigerant flows toward the central portion of the compression chamber.
At the end, as shown in FIG. 2D, the refrigerant compressed thus is discharged through the outlet 12 passed through the fixed scroll 8, and, therefrom, to a condenser through the outlet tube 15, when new refrigerant to be compressed is drawn through the refrigerant inlets 21 and 22 of the compression chamber formed as the scrolls 7 and 8 are engaged.
The foregoing related art scroll compressor is required to compress the refrigerant gradually as the refrigerant goes toward the central portion of the compression chamber, for which it is very important that the wraps 7a and 8a of the orbiting scroll 7 and the fixed scroll 8 are required to be designed to come into a close contact at appropriate positions.
FIGS. 3Axcx9c3C illustrate the steps of a process for forming an orbiting scroll wrap of a related art scroll compressor, referring to which structures of the orbiting scroll wrap 7a and a fixed scroll wrap 8a of the related art scroll compressor will be explained.
Referring to FIG. 3A, a base circle 30 with a radius xe2x80x98axe2x80x99 is drawn on a center on an X-, and Y-axes. Then, an involute curve is drawn, taking one point on a circumference of the base circle 30 at a starting angle xe2x80x98axe2x80x99 from the X-axis as a starting point, i.e., an inner involute curve is drawn. One point on the inner involute curve 31 for the base circle 30 may be expressed with a parameter xe2x80x98xcex8xe2x80x99 as follows.
Xi=axc3x97{cos(xcex8ixe2x88x92xcex1)+xcex8ixc3x97sin(xcex8ixe2x88x92xcex1)},
and
Yi=axc3x97{sin(xcex8ixe2x88x92xcex1)xe2x88x92xcex8ixc3x97cos(xcex8ixe2x88x92xcex1)}
Then, as shown in FIG. 3B, in order to form a thickness of the wrap 7a of the orbiting scroll 7, another involute curve started from a point at xe2x80x98xe2x88x92xcex1xe2x80x99 angle to the X-axis on the circumference of the base circle 30, i.e., an outer involute curve 32, is drawn. One point on the outer involute curve 32 for the base circle 30 may be expressed with a parameter xe2x80x98xcex8xe2x80x99 as follows.
Xo=axc3x97{cos(xcex8o+xcex1)+xcex8oxc3x97sin(xcex8o+xcex1)},
and
Yi=axc3x97{sin(xcex8o+xcex1)xe2x88x92xcex8oxc3x97cos(xcex8o+xcex1)}
A distance of the inner involute curve 31 and the outer involute curve form a thickness xe2x80x98txe2x80x99 for forming the wrap. Thus, as shown in FIG. 3C, upon completion of formation of involute curves, the orbiting scroll 7a can be formed by using the involute curves.
FIGS. 4Axcx9c4C illustrate the steps of a process for forming a fixed scroll wrap of a related art scroll compressor, the fixed scroll wrap 8a is formed in a form having a 180xc2x0 phase difference from the orbiting scroll wrap 7a. That is, a base circle 40 with a radius xe2x80x98axe2x80x99 is drawn in a method identical to the base circle 30 drawn for the orbiting scroll wrap 7a, inner and outer involute curves 41 and 42 are drawn starting from points on the circumference of the base circle 40, and the fixed scroll wrap 8a is formed based on the involute curves 41 and 42 of the scroll compressor, of which detailed explanation will be omitted.
For making appropriate points of the wraps 7a and 8a of the orbiting scroll 7 and the fixed scroll 8 being brought into contact, orbiting radiuses of the involute curves are required to have a relation of (Pxe2x88x922t)/2, where P=2xcfx80a, i.e., a pitch of the wraps 7a and 8a on the scrolls, and xe2x80x98txe2x80x99=2axcex1, i.e., the thickness of the wrap. Accordingly, the compression chamber is formed as the orbiting scroll 7 is made to orbit along an orbiting radius by the motor 5, and the refrigerant drawn into the compression chamber is compressed.
However, the foregoing scroll wrap structures have the following problems in light of the present trend in which the scroll compressor is made smaller while capacity and efficiency are enhanced.
That is, in order to increase a capacity of the related art scroll compressor, there is no way, but to increase a height of the wrap on the scroll, or to increase an overall size of the scroll compressor, which, not only is against the recent trend of making the scroll compressor smaller, but also makes a reliability of the scroll compressor poor, if the heights of the wraps on the scrolls are increased, that makes points of action of a pressure occurred as the refrigerant is compressed higher as much as the increased height of the wrap.
The increased centrifugal force in proportion to an increased mass of the orbiting scroll 7 causes noise heavier when the orbiting scroll 7 and the fixed scroll 8 are in contact, and a light weighted orbiting scroll is essential for extending application of the scroll compressor to a high compression range.
Accordingly, the present invention is directed to a scroll compressor that substantially obviates one or more of the problems due to limitations and disadvantages of the related art.
An object of the present invention is to provide a scroll compressor, which can secure a greater compression space for the same size of scroll compressor while reliability of the scroll compressor is not made poor.
Another object of the present invention is to provide a scroll compressor, which can reduce centrifugal force and noise occurring at the orbiting scroll, and enhance stability of the orbiting scroll.
Additional features and advantages of the invention will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.
To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described, the scroll compressor includes wraps of involute curves on opposite surfaces of an orbiting scroll and a fixed scroll engaged to each other, to form a compression chamber as the orbiting scroll orbits with respect to the fixed scroll, wherein each of the wraps on opposite surfaces of the orbiting scroll and the fixed scroll is formed from two or more involute curves each having a base circle and a point of starting different from each other.
The wraps on opposite surfaces of the orbiting scroll and the fixed scroll includes a first involute curve and a second involute curve of base circles and starting points different from each other employed alternately. The second involute curve preferably has the base circle radius and an angle to an X-axis of the starting point smaller than the first involute curve.
The first involute curve and the second involute curve are used alternately at 180xc2x0 intervals of the involute angles of respective involute curves. The first and second involute curves preferably alternate at 90xc2x0 of involute angle from an outer end of the orbiting scroll wrap or the fixed scroll wrap.
The orbiting scroll wrap employs the second involute curve from 450xc2x0 of involute angle and over, and the fixed scroll wrap employs the second involute curve from 630xc2x0 of involute angle and over.
In another aspect of the present invention, there is provided a scroll compressor including wraps of involute curves on opposite surfaces of an orbiting scroll and a fixed scroll engaged to each other, to form a compression chamber as the orbiting scroll orbits with respect to the fixed scroll, wherein the wraps of the orbiting scroll and the fixed scroll have thickness different from each other.
The wrap of the orbiting scroll has a thickness relatively thinner than the wrap of the fixed scroll.
The wraps of involute curves on the orbiting scroll and the fixed scroll have the same base circle radiuses xe2x80x98axe2x80x99, and different angles of starting points of the wraps of xcex11 and (xcex12 to an X-axis, respectively. The angles of starting points xcex11 and (xcex12 have a relation of 0.5xcex11xe2x89xa6xcex12 less than xcex11.
The wrap of the fixed scroll has a thickness formed relatively thinner than a thickness of the wrap of the orbiting scroll.
The wraps of involute curves on the orbiting scroll and the fixed scroll have the same base circle radiuses and angles of starting points of xcex21 and xcex22 different from each other. The angles of starting points xcex21 and xcex22 of wraps of the orbiting scroll and the fixed scroll respectively have a relation of 0.5xcex21xe2x89xa6xcex22 less than xcex21.
Thus, the scroll compressor of the present invention permits to secure a larger compression space for a same sized scroll compressor while reliability of the scroll compressor is not made poor, to reduce centrifugal force and noise occurring at the orbiting scroll, and improve stability of the orbiting scroll.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed.